1. Field of the Invention
The present invention relates to a floating magnetic head device provided in, for example, a photo-magnetic disk apparatus, and, more particularly, to a magnetic head device which allows the head body to be supported in a stable posture with a minimum number of component parts.
2. Description of the Related Art
FIG. 8 is a partial perspective view of a conventional magnetic head device used in a photo-magnetic disk apparatus.
The magnetic head device is composed of a head body 21 and a supporting member 40 which supports the head body 21.
The head body 21 has a slider 22 which opposes a recording medium and retains a core assembly 25. In FIG. 8, the lower surface of the head body 21 corresponds to the surface opposing the recording medium, whereas the upper surface corresponds to the surface supported by the supporting member 40.
The core assembly 25 is composed of, for example, a core and a coil 30 wound around the core, with a magnetic gap (not shown) in the core assembly 25 appearing from the lower surface of the slider 22.
The supporting member 40 is composed of a load beam 41, an adapter 45, and a flexure 50.
The load beam 41 is formed of a plate spring, and has bent portions 41a at both sides thereof, which extend from the middle to one end of the load beam 41. The bent portions 41a form a rigid structure which allows the base end of the load beam 41 to be resiliently pressed by a predetermined amount. The load beam 41 has a pair of positioning holes 42.
The adapter 45 is .OMEGA.-shaped, and has joint portions 46 and 47, and positioning holes 46a and 47a. With the positioning holes 46a and 47a aligned with the positioning holes 42 of the load beam 41, respectively, the adapter 45 is welded to the load beam 41. The bottom surface of the adapter 45 has a stepped portion, forming two levels thereat. A spherical pivot 49 projects downward from the higher level of the bottom surface, whereas a positioning hole 48 is formed in the lower level of the bottom surface.
The flexure 50 is formed of a thin plate spring. The positioning hole 51 is aligned with the positioning hole 48 in the adapter 45 in order to fix the flexure 50 to the adapter 45, for example, by welding or with an adhesive. The flexure 50 has protrusions 53 formed at both sides of one end thereof, and a tongue 52 formed at the center thereof. The protrusions 53 are inserted in cutouts 24a and 24b provided in the slider 22 in order to affix the tongue 52 of the flexure 50 and the slider 22 together by, for example, using an adhesive.
The upper surface of the tongue 52 of the flexure 50 is brought into contact with the pivot 49 of the adapter 45. The slider 22, due to the resiliency of the flexure 50, is capable of changing its posture freely on the top surface of the pivot 49 as fulcrum.
In general, a photo-magnetic disk is contained in a cartridge to protect its surface. When the cartridge is loaded into a disk apparatus, a shutter of the cartridge is opened, causing a window in the cartridge to be opened. The head body 21 of FIG. 8 enters into the cartridge from the window, and contacts the upper surface of the disk. When the disk in the cartridge rotates, air flowing at the upper surface of the disk causes the head body 21 to take a floating posture, causing the disk to be subjected to a vertical magnetic field through a magnetic gap in the lower surface of the slider 22. The opposite side of the disk is irradiated with laser beams in order to write information onto the disk by either optical modulation or magnetic modulation.
In the conventional magnetic head device, the adapter 45 with a height H is disposed between the load beam 41 and the flexure 50, so that the adapter 45 is used to provide a a load beam 41 height with respect to the head body 21. With the load beam disposed at the outer side of the cartridge, the head body 21, supported by the adapter 45, is capable of contacting the disk in the cartridge from the window of the cartridge.
In the magnetic head device of FIG. 8, however, in order to provide a load beam 41 height with respect to the head body 21, an adapter 45 must be provided, in addition to a load beam 41, a flexure 50, and a head body 21. Thus, a larger number of parts are required to construct the magnetic head device. In addition, an extra operation must be performed, since the adapter 45 must be aligned with the load beam 41 to affix it to the load beam 41. Further, the positioning must be done with greater precision, resulting in higher production costs.
FIG. 9 is a partial side view showing the structure of a conventional magnetic head, in which a load beam height is provided with respect to the head body without using the aforementioned adapter 45.
The load beam 60 of FIG. 9 has a vertical bent surface 61 and a parallel bent surface 62. The vertical bent surface 61 is formed by bending an end portion of the load beam 60 in a direction perpendicular to a disk D. The bent surface 62 is formed by further bending the end portion of the load beam 60 parallel to the disk D. The height of the vertical bent surface 61 is designated by reference character H. A spherical pivot 63 is formed, by molding with pressure, so as to protrude downwardly from the parallel bent surface 62.
A head body 80 is provided below the pivot 63 through a flexure 70. The top portion of the pivot 63 is in contact with the upper surface of the head body 80.
In the magnetic head device of FIG. 9, a height equal to the height H of the adapter 45 can be provided, without using the adapter 45 of FIG. 8, by simply bending one end of the lead beam 60 into the shape of a step.
In the magnetic head device shown in FIG. 9, however, the floating posture of the head body 80 becomes unstable, so that magnetic recording operations cannot be performed accurately.
As shown in FIG. 9, the floating force F acting on the head body 80 as a result of air flowing at the upper surface of the disk D acts on the pivot 63 substantially vertically in the upward direction. Point S (at the top side of the vertical bent surface 61) acts as a fulcrum at one end of the load beam 60. The center of floating force F is not on the vertical line going through the fulcrum S, causing a bending force due to a moment to act on the point S as well as a boundary T between the vertical bent surface 61 and the parallel bent surface 62, where the rigidity is low. This causes the head body 80 to tilt in a rolling direction a more often, so that, for example, the space between the disk D and the head body 80 cannot be stably maintained.
In addition, in the magnetic head device of FIG. 8, positioning holes are formed in the load beam 41, the adapter 45, and the flexure 50. These holes are brought into alignment in order to weld the load beam 41 and the adapter 45 together and to bond a mounting surface 44 of the adapter 45 and the flexure 50 together with an adhesive. Thus, a welding unit is needed to perform the welding operation, so that the manufacturing process becomes complicated, resulting in increased production costs.
Further, when an adhesive is used, the production efficiency tends to be reduced, since the adhesive takes a certain amount of time to dry up completely. In addition, the adhered component parts tend to become misaligned, when, for example, the adhesive gets deformed due to hardening immediately after the component parts are adhered together.